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kotlinlang

I figured out the problem and am posting the solution here in case anyone's interested. The problem is with the Gradle plugin. It can't see the `psiImplUtilClass` file because it hasn't been compiled yet, leading to a chicken and egg problem.

The way to fix that is to set up your build file to run the Grammar Kit task twice, once before you compile your Kotlin sources, and again afterwards but before the generated Java files are compiled.

See <https://github.com/JetBrains/gradle-grammar-kit-plugin/issues/3#issuecomment-588929990>

Ok, it seems like the Gradle plugin is just unusable if your grammar contains rules that implement an interface via method injection and your own code uses those methods on the generated classes. Can't generate code without compiled support class(es), can't compile support class(es) without code generation.